Optical digital pen



FIG. 1 is a front, left side perspective view showing a representative embodiment of our new design, wherein the front, right side perspective view is a mirror image thereof;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a back elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

CLAIM The ornamental design for an optical digital pen, as shown and described. 